Polishing article



ilnited States Patent POLISHING ARTICLE John B. Schroeder, Chicago, Ill.; Gertrude D. Schroeder, administratrix of the estate of said John B. Schroeder, deceased, assignor to Econ-O-Cloth, a partnership consisting of Joan Speck Harvey and Theresa Speck No Drawing. Application June 18, 1956 Serial No. 591,821

3 Claims. (Cl. 51-303) This invention relates to an improved glass polishing article, and more particularly to an improved lens polishing flexible sheet material.

It is one feature of this invention to provide an improved lens polishing flexible sheet which comprises a sheet coated with a mildly abrasive substance including cerium oxide.

A specific feature of this invention is to provide an improved lens polishing article which comprises a cotton fabric coated on at least one side with an abrasive substance comprising cellulose nitrate, a solvent and cerium oxide.

It is well known in the manufacture of optcs for telescopes, microscopes, eye glasses and the like that the rough cut lens must be polished to a high luster to produce regular transparent surfaces. This polishing operation has formerly been done by substances that were time consuming and wasteful. However, by using the polishing article of this invention the polishing time has been noticeably decreased while there is at most only a minfr loss of ingredients. Further, because the polishing article is a s'ngle unit, it may be easily inserted in any of the conventional polishing machines.

The polishing article of this invention consists of a flexible sheet which has been coated with a mildly abrasive substance. The flexible sheet may be any relatively thin material preferably a fabric material and more preferably a cotton fabric having a thickness of, for example, 0.2 millimeter.

The abrasive substance is applied to the flexible sheet in any conventional manner which allows a smooth continuous layer of the substance to be deposited on at least one side of the sheet.

The preferred abrasive substance compr ses cellulose nitrate, cerium oxide and a solvent. The cellulose nitrate which is preferably used has a nitrogen content of from about 11.512.6%. However, it is preferred that a cellulose nitrate having a nitrogen content of from about 11.8-12.2% be used.

The cerium oxide is used in a finely ground powder form. Such a grade of cerium oxide is sold under the trade name Cerox by Lindsay Chemical Corporation of West Chicago, Illinois. The cerium oxide will be present in the abrasive substance in from about to 30 parts by weight for each 20 parts by weight of cellulose nitrate. The preferred cerium oxide is ceric oxide (CeO The solvent used in the abrasive substance may be any 2,865,725 Patented Dec. 23, 1958 of the conventional organic solvents which will dissolve the cellulose nitrate and not have an adverse effect on the flexible sheet. Among those solvents which are suitable for this purpose are acetone, benzene, benzyl alcohol, nbutyl acetate, n-butyl alcohol, cyclohexanone, diacetone alcohol, ethyl acetate, ethyl ether, methyl acetate, methyl alcohol, methyl cyclohexanone, methyl ethyl ketone, npropyl acetate, toluene and xylene. However, the preferred solvent is methyl ethyl ketone. Enough solvent is used to provide a consistency which is suitable for application to the flexible sheet.

In one example of making the polishing material of this invention about 20 parts by weight of cellulose nitrate having a nitrogen content of about 1l.812.2% and about 10 parts by weight of ceric ox de are added to about parts by weight of methyl ethyl ketone. The mixture is thoroughly stirred to provide for complete soluticn of the cellulose nitrate and then is applied to the top surface of a layer of cotton cloth having a thickness of about 0.2 millimeter. The coating is smoothed down by a doctor blade to a uniform but th n coating. The cloth is then allowed to dry thoroughly at which time it is ready to be used.

Having described my invention as related to the embodiments set out herein, it is my intention that the invention be not limited by any of the details of description, unless otherwise specified, but rather be construed broadly within its spirit and scope as set out in the accompanying claims.

I cla'm:

1. A lens polishing article consisting essentially of a cotton fabric of about 0.2 millimeter thickness coated with an abrasive substance consisting essentially of a ratio of about 20 parts by weight of cellulose nitrate having a nitrogen content of from about 11.8-12.2% per about 10 parts of cerium oxide.

2. The lens polishing article of claim 1 wherein said cerium oxide is ceric oxide.

3. A lens polishing article having "a thickness of a fraction of a millimeter contisting essentially of-a textile fabric coated with an abrasive substance consisting essentially of a ratio of about 20 parts by weight of cellulose nitrate per from about 10-30 parts by weight of cerium oxide, the cellulose nitrate having a nitrogen content of from about 11.5-12.6%.

References Cited in the file of this patent UNITED STATES PATENTS 1,615,231 Power Jan. 25, 1927 1,629,259 Crupi May 17, 1927 1,666,701 Hill Apr. 17, 1928 1,736,964 Carlton Nov. 26, 1929 2,024,303 Obrig Dec. 17, 1935 2,450,433 Leeman Oct. 5, 1948 2,554,070 Stead May 22, 1951 2,701,191 Laiberte Feb. 1, 1955 2,744,001 Harman et al. May 1, 1956 OTHER REFERENCES Kroner: Chemical Abstracts, vol. 48, 1954, page 16431:. 

1. A LENS POLISHING ARTICLE CONSISTING ESSENTIALLY OF A COTTON FABRIC OF ABOUT 0.2 MILLIMETER THICKNESS COATED WITH AN ABRASIVE SUBSTANCE CONSISTING ESSENTIALLY OF A RATIO OF ABOUT 20 PARTS BY WEIGHT OF CELLULOSE NITRATE HAVING A NITROGEN CONTENT OF FROM ABOUT 11.8-12.2% PER ABOUT 10 PARTS OF CERIUM OXIDE. 